I received this helmet five years ago and I'm in a position where sadly the money is much more helpful than it sitting on my shelf. I didn't even know of the term "Pickelhaube" or that this was an m1915 variant until yesterday. I was directed here from reddit and mentioned it was appraised at around $1,300 right before I received it. I was informed that sounded a little steep and have since checked my facts. The appraisal was for $800-$1300. I'm here to ask your options of that estimate and also ask for any suggestions on places to sell it (I see you have a sale thread here).

When you say mint do you mean the overall shape of it or the fact that it hasn't had any restoration done to it. I was told no restoration was done but I'd be happy to provide any more detailed pictures and get anybody's opinion on that here. The shape of the helmet is obviously not indistinguishable from when it was brand new 100 years ago. That said, I've looked through a lot of pictures here and I feel like it's in pretty top shape all things considered. Again please tell me if I'm wrong. That's why I'm posting here.

What affects the value most, is condition and rarity. Yours it is the most common of all Pickelhaubes and thus the most commonly seen for sale as well. These go on Ebay for $300 to $600 regularly. Yours is complete so I would venture more towards the top of the scale.

The helmet is in very nice condition. Mint would mean, "like new", or never worn, no marks on the shell lacquer and no missing paint on the cockades (painted side discs), no missing finish on the liner. The helmet is also slightly out of shape as seen from the rear picture.
So a mint helmet would have none of these issues. However, your helmet has some pluses to its condition.....original cockades, original chin strap, complete liner, all metal fittings are present and in good shape. Most of the original finish/paint on the fittings is still there and everything matches. Both visors seem to be still tightly stitched to the shell I see no signs of restoration either. So overall, a very nice complete, example of the Prussian M15 pickelhaube. However, this helmet is the most common in the pickelhaube world. It is traditionally, the "first collector helmet", the one seen most frequently at the military collector shows and on Ebay. Many of these are in far worse condition than yours....most have no chin strap or cockades. That chin strap alone is worth $250+ on Ebay, it is rare for that to be present. So I would value at $600 perhaps a bit more.